Android Open Source - ScalAR Fixed Point Utils

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License

The source code is released under:

GNU General Public License

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Java Source Code

package edu.dhbw.andobjviewer.util;
// ww w  .  j  av a2s .  c  o m
// Much of this is adapted from the beartronics FP lib
public class FixedPointUtils {
  public static final int ONE = 0x10000;
  
  /**
   * Convert a float to  16.16 fixed-point representation
   * @param val The value to convert
   * @return The resulting fixed-point representation
   */
  public static int toFixed(float val) {
    return (int)(val * 65536F);
  }

  /**
   * Convert an array of floats to 16.16 fixed-point
   * @param arr The array
   * @return A newly allocated array of fixed-point values.
   */
  public static int[] toFixed(float[] arr) {
    int[] res = new int[arr.length];
    toFixed(arr, res);
    return res;
  }
  
  /**
   * Convert an array of floats to 16.16 fixed-point
   * @param arr The array of floats
   * @param storage The location to store the fixed-point values.
   */
  public static void toFixed(float[] arr, int[] storage)
  {
    for (int i=0;i<storage.length;i++) {
      storage[i] = toFixed(arr[i]);
    }
  }
  
  /**
   * Convert a 16.16 fixed-point value to floating point
   * @param val The fixed-point value
   * @return The equivalent floating-point value.
   */
  public static float toFloat(int val) {
    return ((float)val)/65536.0f;
  }
  
  /**
   * Convert an array of 16.16 fixed-point values to floating point
   * @param arr The array to convert
   * @return A newly allocated array of floats.
   */
  public static float[] toFloat(int[] arr) {
    float[] res = new float[arr.length];
    toFloat(arr, res);
    return res;
  }
  
  /**
   * Convert an array of 16.16 fixed-point values to floating point
   * @param arr The array to convert
   * @param storage Pre-allocated storage for the result.
   */
  public static void toFloat(int[] arr, float[] storage)
  {
    for (int i=0;i<storage.length;i++) {
      storage[i] = toFloat(arr[i]);
    }
  }
  
  /**
   * Multiply two fixed-point values.
   * @param x
   * @param y
   * @return
   */
  public static int multiply (int x, int y) {
    long z = (long) x * (long) y;
    return ((int) (z >> 16));
  }

  /**
   * Divide two fixed-point values.
   * @param x
   * @param y
   * @return
   */
  public static int divide (int x, int y) {
    long z = (((long) x) << 32);
    return (int) ((z / y) >> 16);
  }  
  
  /**
   * Find the sqrt of a fixed-point value.
   * @param n
   * @return
   */
   public static int sqrt (int n) {
    int s = (n + 65536) >> 1;
    for (int i = 0; i < 8; i++) {
      //converge six times
      s = (s + divide(n, s)) >> 1;
    }
    return s;
   }
}

Java Source Code List